Figure 2

Single nucleotide polymorphism (SNP) density of all rice pre-miRNAs (a), and deeply conserved miRNAs (b), and their flanking regions. The up or down flank region represents a sequence region that is equal to the length of corresponding pre-miRNA, and located immediately adjacent to the pre-miRNA. The differences of SNP density between pre-miRNA and flanking regions were assessed using the ANOVA analysis. Data are reported as the average SNP density value ± s.e. The symbols * and ** designate the significant difference of SNP density in other regions as compared to that in pre-miRNAs at the 0.05 and 0.01 level, respectively.